Synthesis of p-nitrophenyl 2-acetamido-2-deoxy-3-O-β-D-galactopyranosyl-D-galactopyranosides

Reaction of 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide (5) with p-nitrophenyl 2-acetamido-2-deoxy-4,6-O-(p-methoxybenzylidene)-α-D-galactopyranoside (3) under the usual conditions, followed by removal of the p-methoxybenzylidene group and O-deacylation, gave crystalline p-nitrophenyl 2-acetamido-2- deoxy-3-O-β-D-galactopyranosyl-α-D-galactopyranoside (10). The synthesis of p-nitrophenyl 2-acetamido-2-deoxy-3-O-β-D-galactopyranosyl-β-D-galactopyranoside (11) has also been accomplished by a similar reaction-sequence.